13.1: Introduction

Introduction

Above: A traditional Cambodian dance called the Golden Mermaid Dance.

A dancer's nervous system is hard at work during the planning and execution of their movements. Parts of the nervous system are involved in determining how much to flex the hand and when to turn, as well as controlling the muscles throughout the body that make complicated movements possible.

While you are reading this, your nervous system is performing several functions simultaneously. The visual system is processing what is seen on the page, the motor system controls the movement of the eyes and the turning of the pages (or clicks of the mouse), and the prefrontal cortex maintains attention. Even fundamental functions, like breathing and regulation of body temperature, are controlled by the nervous system. A nervous system is an organism’s control center: it processes sensory information from outside (and inside) the body and controls all behaviors—from eating to sleeping to finding a mate.

Organization of the Nervous System

The nervous system is divided into two subsections: the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system is made up of the brain and spinal cord. The peripheral nervous system is the connection between the central nervous system and the rest of the body. The CNS is like the power plant of the nervous system. It creates the signals that control the functions of the body. The PNS is like the wires that go to individual houses. Without those “wires,” the signals produced by the CNS could not control the body (and the CNS would not be able to receive sensory information from the body either).

Above: The nervous system. The central nervous system (CNS), consisting of the brain and spinal cord are highlighted in yellow. The peripheral nervous system (PNS), consisting of the nerves are shown in blue.

The PNS can be broken down into the autonomic nervous system (involuntary), which controls bodily functions without conscious control, and the sensory-somatic nervous system (voluntary), which transmits sensory information from the skin, muscles, and sensory organs to the CNS and sends motor commands from the CNS to the muscles.

Types of Nervous System Cells

The nervous system is made up of neurons, specialized cells that can receive and transmit chemical or electrical signals, and glia or neuroglia, cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons. A neuron can be compared to an electrical wire—it transmits a signal from one place to another. Glia can be compared to the workers at the electric company who make sure wires go to the right places, maintain the wires, and take down wires that are broken. Although glia have been compared to workers, recent evidence suggests that also usurp some of the signaling functions of neurons.

There is great diversity in the types of neurons and glia that are present in different parts of the nervous system. Most neurons contain dendrites, which receive these signals, and axons that send signals to other neurons or tissues. Glia are non-neuronal cells in the nervous system that support neuronal development and signaling. There are several types of glia that serve different functions.

Attributions

• "2016 Phnom Penh, Tradycyjny Kambodżański Pokaz Tańca (137).jpg" by Marcin Konsek is licensed under CC BY-SA 4.0
• "Neurons & Nervous System" by Mohamed Awad is licensed under CC BY-NC-SA 4.0
• "Nervous system diagram.png" by Persian Poet Gal is in the Public Domain
• "Principles of Biology I and II lab manuals" by Dalton State University is licensed under CC BY-SA 4.0